A known seat slide apparatus for a vehicle is disclosed, for example, in JP2011-98610A (which will be hereinafter referred to as Reference 1). As illustrated in FIG. 8, the known seat slide apparatus disclosed in Reference 1 includes a lower rail 110, an upper rail 120 slidably connected relative to the lower rail 110, and a lock member 130 arranged in a space formed between the lower rail 110 and the upper rail 120 and including elasticity (an elastic force). The lower rail 110 includes flanges 111 in a width direction thereof. Locked portions 112 formed substantially in pawls are formed at ends of the flanges 111.
The lock member 130 extends in a longitudinal direction of the lower rail 110 and the upper rail 120 and includes a fixed portion 131 and a lock portion 132. The fixed portion 131 is formed at a first end portion at one side of the lock member 130 in the longitudinal direction while the lock portion 132 is formed at a second end portion at the other side of the lock member 130 in the longitudinal direction. The fixed portion 131 is fixedly attached to a covering wall portion 121 of the upper rail 120. The lock portion 132 is engageable with and disengageable from the locked portions 112 of the lower rail 110. The lock portion 132 is inserted in lock-portion insertion openings 124 formed in side wall portions 122 and side flanges 123 of the upper rail 120 in a width direction thereof. The lock member 130 includes an attachment portion 133 which is arranged at an end of the lock portion 132 so as to extend substantially upward therefrom. An operation member 140 is attached to the attachment portion 133 of the lock member 130. The fixed portion 131 is provided at the first end portion located close to the operation member 140 and the attachment portion 133 is provided at the second end portion located away from the operation member 140.
In a normal state, the lock member 130 is configured so that the lock portion 132 is engaged with the locked portions 112 of the lower rail 110 by the elastic force. In addition, the attachment portion 133 is pressed downward by an operation of the operation member 140; thereby, the lock portion 132 is elastically deformed so as to disengage from the locked portions 112 of the lower rail 110. Thus, a relative movement of the upper rail 120 to the lower rail 110 may be selectively locked or unlocked.
In particular, according to the known seat slide apparatus, as illustrated in FIG. 9A, a fixing hole 125 which includes a substantially annular shape and through which a fixing pin 135 penetrates is formed in the covering wall portion 121 of the upper rail 120. In addition, a movement allowing portion 126 including an elongated shape is continuously formed with the fixing hole 125 so as to connect thereto. The fixed portion 131 of the lock member 130 is connected and fixed to the covering wall portion 121 of the upper rail 120 by the fixing pin 135. In a case where a large load is inputted in the longitudinal direction (in a direction of the relative movement of the upper rail 120 to the lower rail 110), the movement allowing portion 126 is elastically deformed while being pressed by the fixing pin 135, therefore allowing the fixing pin 135 (i.e., the lock member 130) to move relative to the upper rail 120.
In addition, according to the seat slide apparatus, as illustrated in FIG. 9B, a movement restriction portion 124a is continuously formed with each of the lock-portion insertion openings 124 of the upper rail 120 so as to connect to the lock-portion insertion opening 124. The movement restriction portion 124a restricts the lock member 130 from moving in a disengaging direction thereof (i.e., in a direction in which the lock member 130 is disengaged from a locked state with the locked portions 112 of the lower rail 110) when the fixing pin 135 (the lock member 130) in the movement allowing portion 126 moves in the longitudinal direction.
For example, a large load is inputted in the longitudinal direction because of a front collision of the vehicle in a state where the relative movement of the upper rail 120 to the lower rail 110 is locked by the lock member 130. In such case, according to the known seat slide apparatus of Reference 1, the lock member 130 slides rearward relative to the upper rail 120 along with the lower rail 110 in the longitudinal direction while the movement allowing portion 126 of the upper rail 120 is elastically deformed by the fixing pin 135. At this time, the lock member 130 is restricted by the movement restriction portion 124a from moving in the disengaging direction. As a result, the lock member 130 may stably maintain the locked state of the relative movement between the lower rail 110 and the upper rail 120.
According to Reference 1, in order to effectively elastically deform the lock member 130 supported via the first end portion thereof by the covering wall portion 121 of the upper rail 120 and including the elasticity, the lock member 130 is configured so that the attachment portion 133 is provided at the second end portion located away from the operation member 140. In such case, the operation member 140 is elongated to the attachment portion 133; therefore, the length and mass of the operation member 140 may increase.
For example, a known seat slide apparatus to which a lock member made of a material including high rigidity is applied instead of the lock member 130 including the elasticity, is disclosed. In the known seat slide apparatus, an intermediate portion of the lock member in a longitudinal direction thereof is rotatably connected to an upper rail. In the known seat slide apparatus, the lock member including a lock portion and an extending portion is rotatably biased by a biasing member serving as a separate component from the lock member, in a direction in which the lock portion engages with locked portions of a lower rail. Therefore, the lock member may be connected to an operation member by the extending portion extending toward the operation member. In particular, the extending portion is moved upward by an operation of the operation member; thereby, the lock member rotates against a biasing force of the biasing member so as to disengage the lock portion from the locked portions of the lower rail. Thus, according to the aforementioned known seat slide apparatus, a relative movement of the upper rail to the lower rail may be selectively locked and unlocked while increases of the length and mass of the operation member are restricted.
However, for example, in a case where a movement allowing portion similar to the movement allowing portion 126 of Reference 1 is applied to the known seat slide apparatus including the above-mentioned configuration, the movement allowing portion including an elongated hole is continuously formed with a bearing hole of the upper rail so as to connect to the bearing hole by which a shaft portion of the lock member is supported. As a result, a clearance allowance between the bearing hole and the shaft portion of the lock member may increase; therefore, a rotation of the lock member may be unstable.
A need thus exists for a seat slide apparatus for a vehicle, which is not susceptible to the drawbacks mentioned above.